This thesis examines British intelligence collection efforts against the Soviet Union’s nuclear bombers and long-range nuclear ballistic missiles during the period 1949 until 1962. It also analyses the serious intelligence collection problems that were encountered concerning this topic and how successful Britain’s intelligence efforts were in the light of what is now known. This period of Cold War history covers from the Soviet Union’s atomic bomb test through to the Cuban Missile Crisis. The thesis commences with an analysis of the Soviet Union’s nuclear bombers which posed the initial nuclear strike threat to the United Kingdom. It explores how German personnel returning from captivity in the Soviet Union were used by the West to provide information on Soviet military research and how British analysts struggled to gather intelligence on nuclear bombers in a secret police state. The issue of the Soviet ballistic missile threat to the UK is then considered, again by initially examining intelligence provided by German returnees, through to more sophisticated intelligence collection methods such as advanced radar. The papers of the British Joint Intelligence Committee and other government departments were used to examine collection problems and assessments. The role of secret intelligence assessments in the Macmillan government’s decision to cancel the British Blue Streak nuclear missile is also explored. Aerial reconnaissance was a particularly useful intelligence asset. Britain’s clandestine over-flights of the USSR and role in the U-2 programme have only been briefly discussed before. These missions and the UK’s role in covert balloon operations are explored for the first time in a detailed case study. The use of satellite reconnaissance in Britain’s intelligence collection efforts is also assessed. The Colonel Oleg Penkovsky spy case is then analysed as a case study of human intelligence collection and its problems when dealing with Soviet bombers and missiles from 1961-62. This chapter uses declassified American documents to examine the nuclear material he provided, his role in the Cuban Missile Crisis and his overall value to the British and American intelligence agencies. The conclusion is that intelligence collection and analysis evolved significantly from 1949 to 1962 from the use of basic human intelligence to the development of satellite reconnaissance. My thesis, written chronologically, demonstrates that analysts did well to overcome enormous problems when dealing with an extremely difficult intelligence target. At the end of the period they provided far better intelligence collection and analysis on Soviet nuclear weapon delivery systems to British policy makers during a critical period in the Cold War.